The present invention relates to autoregulating heaters and more particularly to a thin, flexible, low mass, inexpensive autoregulating heater primarily for use in soldering to braids of electrical conductors and the like and to rapidly adhering thin, relatively flexible heaters to device having large masses relative to said heater.
The present invention is closely related to U.S. patent application Ser. No. 586,712 filed on Mar. 6, 1984 in the name of Paul F. Busch entitled Flexible Autoregulating Heater with a Latching Mechanism, and assigned to the same assignee as the present application. In application Ser. No. 586,712, there is disclosed a Solder Strap which is relatively flexible and carries a latch so that the strap may be cinched about two overlapping members or braids. The strap includes a temperature autoregulating heater employing, for instance, a heater as disclosed in U.S. Pat. No. 4,256,945 to Carter and Krumme, or the like. The strap is tightened about the device to be soldered by, for instance, a modified Panduit tool that both cinches the strap and applies a constant current thereto. Such a system permits joining of overlapped shield braids of cables used, for instance, in the computer and communications industries. The strap usually, but not necessarily, has solder formed on the surface that contacts the braids, the solder being kept in intimate contact with the braid during the entire operation by the cinching function of the tool. Upon application of current, the solder is quickly melted (fused) well before damage to the insulation under the braids; a long standing problem in such operations.
In the computer field, in particular, it is desirable and, at times essential, to ground insulated and braided cables every 20 to 50 feet, depending upon environment, to suppress electromagnetic interference and control cross-talk, both of which are serious problems in computer terminal-host interconnections and like networks which include communications systems, particularly those used in data transmission. The attachment of a ground strap to such a cable requires removal of the outer insulation and soldering of a lead to the braid. This procedure is known as a "side entry" installation and is quite a troublesome procedure due to the very real danger of damaging the insulation under the braid.
The Solder Strap can be used to apply ground leads to cable braids in many instances, but on installations involving flat cables, problems develop as a result of the tendency of the cable to roll into an annulus when cinched. Also, the solder strap is unnecessarily overdesigned for most such installations, being a relatively high powered device by the very nature of its design for its intended purpose; cinching during soldering large loads (overlapped braids) and providing mechanical reinforcement to the completed solder joint.
In addition the solder strap does not lend itself to utilization with irregular shapes and is not appropriate to use on flat bodies, particularly where the entire area under the heater must be intimately bonded to the adjacent surface such as where it is desired to repair cracks in surfaces.